Process for the production of high purity carbon dioxide

Abstract

Food grade carbon dioxide is produced from oxyfuel fired glassmaking furnace waste gas by a series of steps including quenching the waste gas with aqueous quench liquid, dry-filtering sulfur salt from the gas, scrubbing the filtered gas with aqueous carbonate to convert the remaining sulfur dioxide to an aqueous sulfite suspension and using the suspension as part or all of the above-mentioned aqueous quench liquid, contacting the sulfur dioxide-free waste gas with ammonia in the presence of a catalyst that selectively converts nitrogen oxides to nitrogen, thereby removing substantially all nitrogen oxides from the waste gas, and distilling the resulting waste gas stream thereby producing high purity liquid carbon dioxide and producing an off-gas, which is recycled to the furnace as fuel.

What is claimed is: 
     
       1. A process for recovering carbon dioxide from a feed gas containing carbon dioxide and nitrogen oxides comprising contacting the feed gas with ammonia and a catalyst selected from the group consisting of vanadium, titanium, tungsten, zeolites, platinum, palladium, rhodium, ruthenium, osmium, iridium and mixtures thereof in a selective catalytic reduction zone comprising a series of at least two reactors, with ammonia being introduced into the feed gas entering or in each reactor and converting nitrogen oxides in said feed gas to nitrogen, the waste gas temperature decreasing as the waste gas passes from reactor to reactor, the molar ratio of ammonia to total nitrogen oxides in the waste gas increasing as the waste gas passes from reactor to reactor. 
     
     
       2. The process of claim 1, wherein said selective catalytic reduction zone comprises a series of two reactors, the molar ratio of ammonia to total nitrogen oxides in the waste gas in the first reactor being in the range of about 0.5 to about 1.1, and the temperature of this gas being in the range of about 350 to about 500° C.; and the molar ratio of ammonia to total nitrogen oxides in the waste gas in the second reactor being in the range of about 0.75 to about 2.0, and the temperature of this gas being in the range of about 250 to about 400° C. 
     
     
       3. The process of claim 1, wherein said selective catalytic reduction zone comprises a series of three reactors, the molar ratio of ammonia to total nitrogen oxides in the waste gas in the first reactor being in the range of about 0.5 to about 1.1, and the temperature of this gas being in the range of about 350 to about 500° C.; the molar ratio of ammonia to total nitrogen oxides in the waste gas in the second reactor being in the range of about 0.75 to about 1.5, and the temperature of this gas being in the range of about 300 to about 400° C.; and the molar ratio of ammonia to total nitrogen oxides in the third reactor being in the range of about 1.0 to about 2.0, and the temperature of this gas being in the range of about 250 to about 350° C.